How to grow leek
Allium ampeloprasum · Amaryllidaceae · Vegetable
Leek is a cool-season vegetable in the Amaryllidaceae family, usually started indoors and set out as transplants. It wants full sun (six or more hours of direct light) and steady, even moisture. From sowing to first pick is about 100–150 days. It is one of the toughest crops here, standing through hard frost and often improving for it.
Grower’s note: Long season - start early indoors. Drop seedlings into a 6 in dibbed hole and water in rather than backfilling; hill soil up the stems through summer to blanch the white shank. Stands in the ground through hard frost.
Sowing
Sow about 0.5″ deep, into soil between 45–80°F — germination is quickest near 70°F. Germination takes a week or two (7–14 days). For an early crop, start seed indoors about 10 weeks before your last spring frost and grow it under bright light.
Spacing & layout
Give each plant about 6″ along the row with roughly 12″ between rows. On a square-foot grid that is 9 per square foot. Allow at least 12″ of loose, workable soil for the roots. It grows well in containers at least 12″ deep.
Fitting it to your season
As a cool-season crop, leek does its best growing in the mild weather of spring and fall and tends to bolt or turn bitter in summer heat.
Quick facts
When to plant leek
Companions
Carrot, Celery, Onion, Cabbage
Bush Bean, Pole Bean, Pea
Common problems
Pests: onion maggot, onion thrips, leek moth.
Diseases & disorders: rust, white rot.
Same family (Amaryllidaceae)
Rotate these so they don’t follow each other in the same bed year to year.
Figures are typical home-garden ranges from Cooperative Extension planting guides, cross-checked against multiple state sources. Your variety and conditions will vary.